Many video processing algorithms are formulated as least-squares problems that result in large, sparse linear systems. Solving such systems in real time is very demanding. This paper focuses on reducing the computational complexity of a direct Cholesky-decomposition-based solver. Our approximation scheme builds on the observation that, in well-conditioned problems, many elements in the decomposition nearly vanish. Such elements may be pruned from the dependency graph with mild accuracy degradation. Using an example from image-domain warping, we show that pruning reduces the amount of operations per solve by over 75%, resulting in significant savings in computing time, area or energy.
An approximate computing technique for reducing the complexity of a direct-solver for sparse linear systems in real-time video processing / Schaffner, Michael; Gürkaynak, Frank K.; Smolic, Aljosa; Kaeslin, Hubert; Benini, Luca. - STAMPA. - (2014), pp. 2593082.1-2593082.6. (Intervento presentato al convegno 51st Annual Design Automation Conference, DAC 2014 tenutosi a San Francisco, CA, usa nel 2014) [10.1145/2593069.2593082].
An approximate computing technique for reducing the complexity of a direct-solver for sparse linear systems in real-time video processing
BENINI, LUCA
2014
Abstract
Many video processing algorithms are formulated as least-squares problems that result in large, sparse linear systems. Solving such systems in real time is very demanding. This paper focuses on reducing the computational complexity of a direct Cholesky-decomposition-based solver. Our approximation scheme builds on the observation that, in well-conditioned problems, many elements in the decomposition nearly vanish. Such elements may be pruned from the dependency graph with mild accuracy degradation. Using an example from image-domain warping, we show that pruning reduces the amount of operations per solve by over 75%, resulting in significant savings in computing time, area or energy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.